The present invention relates generally to wideband transceivers, and more particularly to wideband transceivers using multiple phase-locked loops (PLLs).
Ultrawideband (UWB) communication has been proposed for high data rate applications. The data may be transmitted, for example, using direct sequence or orthogonal frequency division multiplexing (OFDM) schemes, and may accommodate data transmission as high as 480 Mb/s or more.
In one such proposal data may be transmitted in the frequency range from 3.168 GHz to 10.560 GHz, subdivided into 5 band groups. Initial efforts for this proposal, however, are generally aimed at operation in a first of these band groups, which provides for data transmission in three sub-bands over the frequency range of 3.168 GHz to 4.752 GHz. The three sub-bands are centered at 3.432 GHz, 3.960 GHz, and 4.488 GHz, and each occupy 528 MHz of spectrum.
Communication of data on these sub-bands may be performed with a transmitter and a receiver switching from sub-band to sub-band on a periodic basis, and doing so while communicating data. A guard interval may be provided to account for transient effects while the transmitter and receiver switch sub-bands. The sub-band switching time, however, may not be great, for example in the range of 9 nanoseconds, and it may be difficult for the transmitter and receiver to effectively change sub-bands within an allocated time period.
In view of potentially short sub-band switching time, use of wideband PLLs might be difficult, particularly if the wideband PLL can not quickly lock on to a correct data rate. Similarly, use of single sideband mixers may also generate signals containing excess harmonic distortion and otherwise dissipate excess power, either through filtering of the signals, amplification of data signals, or both.